Refrigerator appliance with a caloric heat pump

ABSTRACT

A refrigerator appliance includes a fresh food cold side heat exchanger positioned within a cabinet at a fresh food chamber and a freezer cold side heat exchanger positioned within the cabinet at a freezer chamber. Working fluid is flowable through a caloric material within a regenerator housing. The refrigerator appliances also includes features for flowing the working fluid from the regenerator housing to the fresh food cold side heat exchanger and for separately flowing the working fluid from the regenerator housing to the freezer cold side heat exchanger.

FIELD OF THE INVENTION

The present subject matter relates generally to heat pumps, such as magneto-caloric heat pumps.

BACKGROUND OF THE INVENTION

Conventional refrigeration technology typically utilizes a heat pump that relies on compression and expansion of a fluid refrigerant to receive and reject heat in a cyclic manner so as to effect a desired temperature change or transfer heat energy from one location to another. This cycle can be used to receive heat from a refrigeration compartment and reject such heat to the environment or a location that is external to the compartment. Other applications include air conditioning of residential or commercial structures. A variety of different fluid refrigerants have been developed that can be used with the heat pump in such systems.

While improvements have been made to such heat pump systems that rely on the compression of fluid refrigerant, at best such can still only operate at about forty-five percent or less of the maximum theoretical Carnot cycle efficiency. Also, some fluid refrigerants have been discontinued due to environmental concerns. The range of ambient temperatures over which certain refrigerant-based systems can operate may be impractical for certain locations. Other challenges with heat pumps that use a fluid refrigerant exist as well.

Magneto-caloric materials (MCMs), i.e. materials that exhibit the magneto-caloric effect, provide a potential alternative to fluid refrigerants for heat pump applications. In general, the magnetic moments of MCMs become more ordered under an increasing, externally applied magnetic field and cause the MCMs to generate heat. Conversely, decreasing the externally applied magnetic field allows the magnetic moments of the MCMs to become more disordered and allow the MCMs to absorb heat. Some MCMs exhibit the opposite behavior, i.e. generating heat when the magnetic field is removed (which are sometimes referred to as para-magneto-caloric material but both types are referred to collectively herein as magneto-caloric material or MCM). The theoretical Carnot cycle efficiency of a refrigeration cycle based on an MCMs can be significantly higher than for a comparable refrigeration cycle based on a fluid refrigerant. As such, a heat pump system that can effectively use an MCM would be useful.

Challenges exist to the practical and cost competitive use of an MCM, however. In addition to the development of suitable MCMs, equipment that can attractively utilize an MCM is still needed. Currently proposed equipment may require relatively large and expensive magnets, may be impractical for use in e.g., appliance refrigeration, and may not otherwise operate with enough efficiency to justify capital cost.

Accordingly, a heat pump system that can address certain challenges, such as those identified above, would be useful. Such a heat pump system that can also be used in a refrigerator appliance would also be useful.

BRIEF DESCRIPTION OF THE INVENTION

The present subject matter provides a refrigerator appliance a fresh food cold side heat exchanger positioned within a cabinet at a fresh food chamber and a freezer cold side heat exchanger positioned within the cabinet at a freezer chamber. Working fluid is flowable through a caloric material within a regenerator housing. The refrigerator appliances also includes features for flowing the working fluid from the regenerator housing to the fresh food cold side heat exchanger and for separately flowing the working fluid from the regenerator housing to the freezer cold side heat exchanger. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In a first exemplary embodiment, a refrigerator appliance is provided. The refrigerator appliance includes a cabinet that defines a fresh food chamber and a freezer chamber. A fresh food cold side heat exchanger is positioned within the cabinet at the fresh food chamber. The fresh food chamber is chillable with air from the fresh food cold side heat exchanger. A freezer cold side heat exchanger is positioned within the cabinet at the freezer chamber. The freezer chamber is chillable with air from the freezer cold side heat exchanger. A regenerator housing has a first cold side connection and a second cold side connection. The first cold side connection is separate from the second cold side connection on the regenerator housing. A caloric material is disposed within the regenerator housing. Working fluid is flowable through the caloric material within the regenerator housing. The working fluid is flowable from the regenerator housing to the fresh food cold side heat exchanger via the first cold side connection and to the freezer cold side heat exchanger via the second cold side connection.

In a second exemplary embodiment, a refrigerator appliance is provided. The refrigerator appliance includes a cabinet that defines a fresh food chamber and a freezer chamber. A fresh food cold side heat exchanger is positioned within the cabinet at the fresh food chamber. The fresh food chamber is chillable with air from the fresh food cold side heat exchanger. A freezer cold side heat exchanger is positioned within the cabinet at the freezer chamber. The freezer chamber is chillable with air from the freezer cold side heat exchanger. The refrigerator appliance also includes a regenerator housing. A caloric material is disposed within the regenerator housing. Working fluid flowable through the caloric material within the regenerator housing. The refrigerator appliances also includes means for flowing the working fluid from the regenerator housing to the fresh food cold side heat exchanger and for separately flowing the working fluid from the regenerator housing to the freezer cold side heat exchanger.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 is a refrigerator appliance in accordance with an exemplary embodiment of the present disclosure.

FIG. 2 is a schematic illustration of certain components of a heat pump system positioned in the exemplary refrigerator appliance of FIG. 1.

FIG. 3 is a schematic illustration of certain components of the heat pump system of FIG. 2, with a first stage of MCM within a magnetic field and a second stage of MCM out of a magnetic field, in accordance with an exemplary embodiment of the present disclosure.

FIG. 4 is a schematic illustration of certain components of the exemplary heat pump system of FIG. 2, with the first stage of MCM out of the magnetic field and the second stage of MCM within the magnetic field.

FIGS. 5 and 6 are schematic illustrations of certain components of the heat pump system of FIG. 2, in accordance with another exemplary embodiment of the present disclosure.

FIG. 7 provides a schematic view of an exemplary caloric heat pump according to another exemplary embodiment of the present subject matter.

FIG. 8 is a schematic diagram illustrating various positions and movements there-between of MCM stages in accordance with an exemplary embodiment of the present disclosure.

FIG. 9 provides a schematic view of certain components of the exemplary caloric heat pump of the heat pump system of FIG. 2.

FIG. 10 provides a schematic view of certain components of an exemplary caloric heat pump according to another exemplary embodiment of the present subject matter.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The present subject matter is directed to a caloric heat pump system for heating or cooling an appliance, such as a refrigerator appliance. While described in greater detail below in the context of a magneto-caloric heat pump system, one of skill in the art using the teachings herein will recognize that other suitable caloric materials may be used in a similar manner to heat or cool an appliance, i.e., apply a field, move heat, remove the field, move heat. For example, electro-caloric material heats up and cools down within increasing and decreasing electric fields. As another example, elasto-caloric material heats up and cools down when exposed to increasing and decreasing mechanical strain. As yet another example, baro-caloric material heats up and cools down when exposed to increasing and decreasing pressure. Such materials and other similar caloric materials may be used in place of or in addition to the magneto-caloric material described below to heat or cool liquid/water within an appliance. Thus, caloric material is used broadly herein to encompass materials that undergo heating or cooling when exposed to a changing field from a field generator, where the field generator may be a magnet, an electric field generator, an actuator for applying mechanical stress or pressure, etc.

Referring now to FIG. 1, an exemplary embodiment of a refrigerator appliance 10 is depicted as an upright refrigerator having a cabinet or casing 12 that defines a number of internal storage compartments or chilled chambers. In particular, refrigerator appliance 10 includes upper fresh-food compartments 14 having doors 16 and lower freezer compartment 18 having upper drawer 20 and lower drawer 22. Drawers 20, 22 are “pull-out” type drawers in that they can be manually moved into and out of freezer compartment 18 on suitable slide mechanisms. Refrigerator 10 is provided by way of example only. Other configurations for a refrigerator appliance may be used as well including appliances with only freezer compartments, only chilled compartments, or other combinations thereof different from that shown in FIG. 1. In addition, the heat pump and heat pump system of the present disclosure is not limited to refrigerator appliances and may be used in other applications as well such as e.g., air-conditioning, electronics cooling devices, and others. Thus, it should be understood that while the use of a heat pump and heat pump system to provide cooling within a refrigerator is provided by way of example herein, the present disclosure may also be used to provide for heating applications as well.

FIG. 2 is a schematic view of various components of refrigerator appliance 10, including refrigeration compartments 30 (e.g., fresh-food compartments 14 and freezer compartment 18) and a machinery compartment 40. Refrigeration compartment 30 and machinery compartment 40 include a heat pump system 52 having a first cold side heat exchanger 32 positioned in refrigeration compartments 30 for the removal of heat therefrom. A heat transfer fluid such as e.g., an aqueous solution, flowing within first cold side heat exchanger 32 receives heat from refrigeration compartment 30 thereby cooling contents of refrigeration compartment 30.

As may be seen in FIG. 2, heat pump system 52 also has a second cold side heat exchanger 33. Second cold side heat exchanger 33 operates in parallel with first cold side heat exchanger 32 to cool refrigeration compartments 30, e.g., a respective one of fresh-food compartment 14 and freezer chamber 18. For example, first cold side heat exchanger 32 may be positioned at or adjacent fresh-food compartment 14, and air from first cold side heat exchanger 32 may cool fresh-food compartment 14. Conversely, second cold side heat exchanger 33 may be positioned at or adjacent freezer compartment 18, and air from second cold side heat exchanger 33 may cool freezer compartment 18.

The heat transfer fluid flows out of first cold side heat exchanger 32 by line 44 to heat pump 100. As will be further described herein, the heat transfer fluid receives additional heat from magneto-caloric material (MCM) in heat pump 100 and carries this heat by line 48 to a third or hot side heat exchanger 34. Heat is released to the environment, machinery compartment 40, and/or other location external to refrigeration compartment 30 using hot side heat exchanger 34. A fan 36 may be used to create a flow of air across hot side heat exchanger 34 and thereby improve the rate of heat transfer to the environment. A pump or pumps (not shown) cause the heat transfer fluid to recirculate in heat pump system 52. Motor 28 is in mechanical communication with heat pump 100 and is operable to provide relative motion between a field generator and a regenerator housing, as discussed in greater detail below.

From hot side heat exchanger 34, the heat transfer fluid returns by line 50 to heat pump 100 where, as will be further described below, the heat transfer fluid loses heat to the MCM in heat pump 100. The now colder heat transfer fluid flows by line 46 to first cold side heat exchanger 32 to receive heat from refrigeration compartment 30 and repeat the cycle as just described.

The heat transfer fluid may flow to second cold side heat exchanger 33 in the manner described above for first cold side heat exchanger 32. For example, heat transfer fluid flows by line 96 to second cold side heat exchanger 33 from heat pump 100, and heat transfer fluid flows by line 98 to heat pump 100 from second cold side heat exchanger 33. Heat pump system 52 is provided by way of example only. Other configurations of heat pump system 52 may be used as well. For example, lines 44, 46, 48, 50, 96, 98 provide fluid communication between the various components of heat pump system 52 but other heat transfer fluid recirculation loops with different lines and connections may also be employed. Still other configurations of heat pump system 52 may be used as well.

Refrigerator appliance 10 also includes features for regulating air flow across first cold side heat exchanger 32 to fresh-food compartment 14 and across second cold side heat exchanger 33 to freezer compartment 18. As may be seen in FIG. 2, first cold side heat exchanger 32 is positioned within a first heat exchanger compartment 60 that is defined within cabinet 12, e.g., between fresh-food compartments 14 and freezer compartment 18. Fresh-food compartment 14 is contiguous with first heat exchanger compartment 60 through a fresh food duct 62. Thus, air may flow between fresh-food compartment 14 and first heat exchanger compartment 60 via fresh food duct 62. Second cold side heat exchanger 33 is positioned within a second heat exchanger compartment 61 that is defined within cabinet 12, e.g., between fresh-food compartments 14 and freezer compartment 18. Freezer compartment 18 is contiguous with second heat exchanger compartment 61 through a freezer duct 64. Thus, air may flow between freezer compartment 18 and second heat exchanger compartment 61 via freezer duct 64. First heat exchanger compartment 61 may be separate from second heat exchanger compartment 61 within cabinet 12. In addition, fresh food duct 62 may be separate from freezer duct 64 within cabinet 12, in certain exemplary embodiments.

Refrigerator appliance 10 also includes a fresh food fan 66 and a freezer fan 68. Fresh food fan 66 may be positioned at or within fresh food duct 62. Fresh food fan 66 is operable to force air flow between fresh-food compartment 14 and first heat exchanger compartment 60 through fresh food duct 62. Fresh food fan 66 may thus be used to create a flow of air across first cold side heat exchanger 32 and thereby improve the rate of heat transfer. Freezer fan 68 may be positioned at or within freezer duct 64. Freezer fan 68 is operable to force air flow between freezer compartment 18 and second heat exchanger compartment 61 through freezer duct 64. Freezer fan 68 may thus be used to create a flow of air across second cold side heat exchanger 33 and thereby improve the rate of heat transfer.

Operation of heat pump system 52 and fresh food fan 66 allows chilled air from first cold side heat exchanger 32 to cool fresh-food compartment 14, e.g., to about forty degrees Fahrenheit (40° F.). Similarly, operation of heat pump system 52 and freezer fan 68 allows chilled air from second cold side heat exchanger 33 to cool freezer compartment 18, e.g., to about negative ten degrees Fahrenheit (−10° F.). Thus, first cold side heat exchanger 32 may chill fresh-food compartment 14 and second cold side heat exchanger 33 may chill freezer compartment 18 during operation of heat pump system 52. In such a manner, first and second cold side heat exchangers 32, 33 may separately cool fresh-food compartments 14 and freezer compartment 18.

FIGS. 3 through 7 illustrate various exemplary heat pumps 100 and components thereof, and the use of such heat pumps 100 with heat pump system 52, in accordance with exemplary embodiments of the present disclosure. Heat pump 100 shown in FIGS. 3 through 6 may be suitable for use within a linear reciprocating caloric heat pump while heat pump 100 shown in FIG. 7 may be suitable for use within a rotatory caloric heat pump. Thus, it will be understood that the present subject matter may be used in or with any suitable heat pump, including linear caloric heat pumps and rotary caloric heat pumps, and the example heat pumps 100 provided herein are not intended to limit the present subject matter to any particular heat pump arrangement.

Referring now to heat pump 100 in FIGS. 3 and 4 and FIGS. 5 and 6, heat pump 100 may include a plurality of stages, each of which includes a magneto-caloric material (MCM). In exemplary embodiments, such MCM stages may be provided in pairs, each of which may for example include a first stage 130 and a second stage 132. Each stage 130, 132 may include one or more different types of MCM. Further, the MCM(s) provided in each stage 130, 132 may be the same or may be different. Stages 130, 132 may be disposed within a regenerator housing 140. Regenerator housing 140 along with stages 130, 132 and optional insulative materials may collectively be referred to as a regenerator assembly. As illustrated, in exemplary embodiments, regenerator housing 140 may include two stages 130, 132. Alternatively, three, four or more stages may be provided in regenerator housing 140. In particular, as shown in FIG. 7, heat pump 100 may include a plurality of first stages 130 within regenerator housing 140, e.g., eight first stages 130 uniformly distributed about a rotation axis of heat pump 100.

Each stage 130, 132 may extend between a first end 134 and a second end 136. As discussed herein, working fluid (also referred to herein as heat transfer fluid or fluid refrigerant) may flow through stages 130, 132 during operation of heat pump 100 generally between first and second ends 134, 136 of stages 130, 132. As discussed in greater detail below, heat pump 100 includes features for drawing-off or removing the working fluid from the stage 130, 132 at various locations along a transverse direction T.

Heat pumps 100 also includes one or more magnet assemblies (not shown), each of which creates a magnetic field M (FIG. 8), or other suitable field generators. The regenerator housing 140 and magnet assembly(s) may be movable relative to each other. In exemplary embodiments as shown, for example, regenerator housing 140 is movable relative to the magnet assembly. Alternatively, however, the magnet assembly may be movable relative to regenerator housing 140. Such relative movement between regenerator housing 140 and an associated magnet assembly causes movement of each stage 130, 132 into the magnetic field M and out of the magnetic field M. As discussed herein, movement of a stage 130, 132 into the magnetic field M may cause the magnetic moments of the material to orient and the MCM to heat (or alternatively cool) as part of the magneto-caloric effect. When one of stages 130, 132 is out of the magnetic field M, the MCM may thus cool (or alternatively heat) due to disorder of the magnetic moments of the material.

For example, referring to FIGS. 3 through 6, regenerator housing 140 may be movable linearly between a first position and a second position. In the first position, regenerator housing 140 may be positioned such that first stage 130 disposed within regenerator housing 140 is within the magnetic field M and second stage 132 disposed within regenerator housing 140 is out of the magnetic field M. Notably, being out of the magnetic field M means that second stage 132 is generally or substantially uninfluenced by the magnets and resulting magnetic field M. Accordingly, the MCM of the stage as a whole may not be actively heating (or cooling) as it would if within the magnetic field M (and instead may be actively or passively cooling (or heating) due to such removal of the magnetic field M). In the second position, regenerator housing 140 may be positioned such that first stage 130 disposed within regenerator housing 140 is out of the magnetic field M and second stage 132 disposed within regenerator housing 140 is within the magnetic field M. Similarly, with reference to FIG. 7, regenerator housing 140 may also be rotatable such that one portion of stages 130 are within the magnetic field M and the remainder of the stages 130 are out of the magnetic field M in the first position and vice versa in the second position. Movement of a regenerator housing 140 may be caused by operation of motor 26. Motor 26 may be in mechanical communication with regenerator housing 140 and configured for linearly or rotatably moving regenerator housing 140 or the magnet assemblies.

Referring also to FIG. 2, in some exemplary embodiments, lines 44, 46, 48, 50, 96, 98 may facilitate the flow of working fluid between heat exchangers 32, 33, 34 and heat pump 100. In exemplary embodiments, lines 44, 46, 48, 50, 96, 98 may facilitate the flow of working fluid between heat exchangers 32, 33, 34 and stages 130, 132 of heat pump 100. For example, a line 44 (e.g., a first cold side working fluid return conduit) may extend between first cold side heat exchanger 32 and regenerator housing 140, such that working fluid from an outlet of heat exchanger 32 flows through line 44 to regenerator housing 140. A line 46 (e.g., a first cold side working fluid supply conduit) may extend between regenerator housing 140 and first cold side heat exchanger 32, such that working fluid from regenerator housing 140 flows through line 46 to an inlet of heat exchanger 32. A line 50 (e.g., hot side working fluid return conduit) may extend between hot side heat exchanger 34 and regenerator housing 140, such that working fluid from an outlet of heat exchanger 34 flows through line 50 to regenerator housing 140. A line 48 (e.g., hot side working fluid supply conduit) may extend between regenerator housing 140 and hot side heat exchanger 34, such that working fluid from regenerator housing 140 flows through line 48 to an inlet of heat exchanger 34. A line 96 (e.g., a second cold side working fluid return conduit) may extend between second cold side heat exchanger 33 and regenerator housing 140, such that working fluid from an outlet heat exchanger 33 flows through line 96 to regenerator housing 140. A line 98 (e.g., second cold side working fluid supply conduit) may extend between regenerator housing 140 and an inlet second cold side heat exchanger 33, such that working fluid from regenerator housing 140 flows through line 98 to heat exchanger 33.

Notably, check valves 190 may in some exemplary embodiments be provided on the various lines 44, 46, 48, 50, 96, 98 to prevent backflow there-through. Exemplary positions and orientations of check valves 190 on lines 44, 46, 96, 98 are shown in FIGS. 3 through 6. Check valves 190, in combination with differential pressures during operation of heat pump 100, may thus generally prevent flow through the improper flow path when working fluid is being actively flowed through heat pump 100, e.g., such that working fluid flows through stages 130, 132 in the manner described below in the context of FIG. 8. In particular, with reference to the exemplary embodiment shown in FIGS. 3 and 4, check valves 190 are positioned on lines 44, 46, 96, 98 to provide the flow of working fluid shown with solid lines 44, 46, 96, 98 in FIG. 3 during the compression stroke of pump 170 and to conversely provide the flow of working fluid shown with solid lines 44, 46, 96, 98 in FIG. 4 during the compression stroke of pump 172. Heat pump system 52 may also include a restriction 192 on one of lines 44, 46, 96, 98. Restriction 192 may assist with balancing working fluid flow between first and second cold side heat exchangers 32, 33.

Heat pump system 52 may also include at least one pump, such as pump 170 and/or pump 172, operable to flow the working fluid through lines 44, 46, 48, 50, 96, 98. With reference to FIGS. 3 through 6, first and second pumps 170, 172 may be synchronized such that one of first and second pumps 170, 172 is on a compression stroke while the other of first and second pumps 170, 172 is on a suction stroke. Such synchronization may assist with maintaining a constant volume of working fluid within heat pump system 52. For example, in FIGS. 3 and 5, first pump 170 is shown at a bottom dead center position while second pump 172 is shown at a top dead center position. Conversely, in FIGS. 4 and 6, first pump 170 is shown at the top center position while second pump 172 is shown at the bottom center position. Thus, first and second pumps 170, 172 may be synchronized to operate completely out of phase with one another. With reference to FIG. 7, first pump 170 may also operate continuously to flow working through first stages 130 during rotation of regenerator housing 140.

FIG. 8 illustrates an exemplary method of the present disclosure using a schematic representation of associated stages 130, 132 of MCM during dwelling in and movement between the various positions as discussed herein. With regard to first stage 130, during step 200, which corresponds to the first position, stage 130 is fully within magnetic field M, which causes the magnetic moments of the material to orient and the MCM to heat as part of the magneto caloric effect. Further, pump 170 is activated to actively flow working fluid. As indicated by arrow Q_(H-OUT), working fluid in stage 130, now heated by the MCM, can travel out of stage 130 and along line 48 to hot side heat exchanger 34. At the same time, and as indicated by arrow Q_(H-IN), working fluid from first cold side heat exchanger 32 flows into stage 130 from line 44. Because working fluid from first cold side heat exchanger 32 is relatively cooler than the MCM in stage 130, the MCM will lose heat to the working fluid.

In step 202, stage 130 is moved from the first position to the second position in the first transition. During the time in the first transition, working fluid dwells in the MCM of stage 130. More specifically, the working fluid does not actively flow through stage 130.

In step 204, stage 130 is in the second position and thus out of magnetic field M. The absence or lessening of the magnetic field is such that the magnetic moments of the material become disordered and the MCM absorbs heat as part of the magnetocaloric effect. Further, pump 172 is activated to actively flow working fluid. As indicated by arrow Q_(C-OUT), working fluid in stage 130, now cooled by the MCM, can travel out of stage 130 and along line 46 to first cold side heat exchanger 32. At the same time, and as indicated by arrow Q_(C-IN), working fluid from hot side heat exchanger 34 flows into stage 112 from line 50 when stage 130 is in the second transition. Because working fluid from hot side heat exchanger 34 is relatively warmer than the MCM in stage 130, the MCM will lose some of its heat to the working fluid. The working fluid now travels along line 46 to first cold side heat exchanger 32 to receive heat and cool refrigeration compartment 30.

In step 206, stage 130 is moved from the second position to the first position in the second transition. During the time in the second transition, the working fluid dwells in the MCM of stage 130. More specifically, the working fluid does not actively flow through stage 130.

With regard to second stage 132, during step 200, which corresponds to the first position, second stage 132 is out of magnetic field M. The absence or lessening of the magnetic field is such that the magnetic moments of the material become disordered and the MCM absorbs heat as part of the magneto-caloric effect. Further, pump 170 is activated to actively flow working fluid. As indicated by arrow Q_(C-OUT), working fluid in stage 132, now cooled by the MCM, can travel out of stage 132 and along line 46 to first cold side heat exchanger 32. At the same time, and as indicated by arrow Q_(C-IN), working fluid from hot side heat exchanger 34 flows into stage 112 from line 50 when stage 132 is in the second transition. Because working fluid from hot side heat exchanger 34 is relatively warmer than the MCM in stage 132, the MCM will lose some of its heat to the working fluid. The working fluid now travels along line 46 to first cold side heat exchanger 32 to receive heat and cool the refrigeration compartment 30.

In step 202, stage 132 is moved from the first position to the second position in the first transition. During the time in the first transition, the working fluid dwells in the MCM of stage 132. More specifically, the working fluid does not actively flow through stage 132.

In step 204, stage 132 is in the second position and thus fully within magnetic field M, which causes the magnetic moments of the material to orient and the MCM to heat as part of the magneto caloric effect. Further, pump 172 is activated to actively flow working fluid. As indicated by arrow Q_(H-OUT), working fluid in stage 132, now heated by the MCM, can travel out of stage 132 and along line 48 to hot side heat exchanger 34. At the same time, and as indicated by arrow Q_(H-IN), working fluid from first cold side heat exchanger 32 flows into stage 132 from line 44. Because working fluid from first cold side heat exchanger 32 is relatively cooler than the MCM in stage 132, the MCM will lose heat to the working fluid.

In step 206, stage 132 is moved from the second position to the first position in the second transition. During the time in the second transition, working fluid dwells in the MCM of stage 132. More specifically, the working fluid does not actively flow through stage 132. It will be understood that while described above in the context of first cold side heat exchanger 32, second cold side heat exchanger 33 may be configured and operate in the same or similar manner to cool freezer compartment 18 as described above for first cold side heat exchanger 32 to cool fresh-food compartment 14 unless otherwise stated.

FIG. 9 provides a schematic view of certain components of heat pump 100 of heat pump system 52. As discussed in greater detail below, heat pump 100 includes features for drawing working fluid from regenerator housing 140 at a plurality of locations along a length H of first and second stages 130, 132. For example, when heat pump system 52 operates to cool fresh-food compartment 14, the working fluid exits regenerator housing 140 at a first location along the length H of first stage 130. Conversely, the working fluid exits regenerator housing 140 at a second location (different than the first location) along the length H of first stage 130 when heat pump system 52 operates to cool freezer compartment 18. By drawing the working fluid from different locations depending upon which chamber of refrigerator appliance 10 is being cooled by heat pump system 52, heat pump system 52 may operate more efficiently than if the working fluid were drawn from a single location on regenerator housing. While described in greater detail below in the context of first stage 130, it will be understood that regenerator housing 140 may be configured in a similar manner at second stage 132 to allow multiple working fluid draw location along a length of second stage 132.

As may be seen in FIG. 9, first stage 130 is disposed within regenerator housing 140. In particular, first stage 130 may have a length H along a longitudinal direction O, e.g., that is parallel to the transverse direction T, within regenerator housing 140. Working fluid is flowable through first stage 130 within regenerator housing 140. Regenerator housing 140 is also connected to first cold side heat exchanger 32 such that working fluid is flowable from regenerator housing 140 to first cold side heat exchanger 32. In particular, regenerator housing 140 includes a first cold side connection 150. Lines 44, 46 are connected to regenerator housing 140 at first cold side connection 150. Thus, working fluid is flowable from regenerator housing 140 to an inlet of first cold side heat exchanger 32 via line 46 at first cold side connection 150 (also shown in FIGS. 3 through 6 during operation of pumps 170, 172 and in FIG. 7 during operation of pump 170), and working fluid is flowable from an outlet of first cold side heat exchanger 32 to regenerator housing 140 via line 44 at first cold side connection 150. The flow of working fluid through lines 44, 46 within heat pump system 52 may also be seen in FIGS. 3 through 6 during operation of pumps 170, 172 and in FIG. 7 during operation of pump 170.

In addition, regenerator housing 140 is also connected to second cold side heat exchanger 33 such that working fluid is flowable from regenerator housing 140 to second cold side heat exchanger 33. In particular, regenerator housing 140 includes a second cold side connection 154. Lines 96, 98 are connected to regenerator housing 140 at second cold side connection 154. Thus, working fluid is flowable from regenerator housing 140 to an inlet of second cold side heat exchanger 33 via line 98 at second cold side connection 154, and working fluid is flowable from an outlet of second cold side heat exchanger 33 to regenerator housing 140 via line 96 at second cold side connection 154. Thus, lines 96, 98 may be in parallel with lines 44, 46. The flow of working fluid through lines 96, 98 within heat pump system 52 may also be seen in FIGS. 3 through 6 during operation of pumps 170, 172 and in FIG. 7 during operation of pump 170.

Regenerator housing 140 is also connected to hot side heat exchanger 34 such that working fluid is flowable between regenerator housing 140 and hot side heat exchanger 34. In particular, regenerator housing 140 has a hot side connection 152. Lines 48, 50 are connected to regenerator housing 140 at hot side connection 152. Thus, working fluid is flowable from regenerator housing 140 to an inlet of hot side heat exchanger 34 via line 48 at hot side connection 152, and working fluid is flowable from an outlet of hot side heat exchanger 34 to regenerator housing 140 via line 50 at hot side connection 152. The flow of working fluid through lines 48, 50 within heat pump system 52 may also be seen in FIGS. 3 through 6 during operation of pumps 170, 172 and in FIG. 7 during operation of pump 170.

Hot side connection 152 is spaced from first and second cold side connections 150, 154 on regenerator housing 140, e.g., along the longitudinal direction O. For example, hot side connection 152 may be positioned at first end portion 144 of regenerator housing 140, and second cold side connection 154 may be positioned at second end portion 146 of regenerator housing 140. First cold side connection 150 may be positioned between hot side connection 152 and second cold side connection 154, e.g., along the longitudinal direction O. By spacing first and second cold side connections 150, 154 on regenerator housing 140, first cold side connection 150 may draw working fluid from regenerator housing 140 at a different location along the length H of first stage 130 relative to second cold side connection 154. In particular, the working fluid exits regenerator housing 140 at the first cold side connection 150 when heat pump system 52 operates to cool fresh-food compartment 14, and the working fluid exits regenerator housing 140 at the second cold side connection 154 when heat pump system 52 operates to cool freezer compartment 18.

First cold side connection 150 is closer to hot side connection 152 than second cold side connection 154, e.g., along the longitudinal direction O. Thus, the working fluid may flow through less of the length H of first stage 130 to first cold side connection 150 compared to second cold side connection 154. In such a manner cooling of the working fluid by first stage 130 may be regulated. In particular, first stage 130 may reduce the temperature of the working fluid more when the working fluid exits regenerator housing 140 at second cold side connection 154 compared to when the working fluid exits regenerator housing 140 at first cold side connection 150. It will be understood that additional cold side connections may be positioned at any other suitable location in alternative exemplary embodiments. For example, if refrigerator appliance 10 has a deli tray, an icemaker, a cold water dispenser, a quick freezer feature, etc., a respective cold side connection may be provided for each additional component of refrigerator appliance.

The multiple cold side connections on regenerator housing 140 allows working fluid to be pulled-off at multiple locations when cooling the first and second cold side heat exchangers 32, 33. By pulling the working fluid from one of the cold side connections, each compartment may be cooled to a respective set temperature. As may be seen in FIGS. 2 through 7, heat pump system 52 may utilize multiple cold side heat exchangers 32, 33 to cool multiple refrigeration compartments 30, and the first and second cold side connections 150, 154 on regenerator housing 140 allow working fluid to be pulled-off at multiple locations to cold side heat exchangers 32, 33. By adjusting which one of first and second cold side connections 150, 154 through which the working fluid flows, each compartment may be cooled to a respective set temperature. When time-sharing between negative ten degrees Fahrenheit (−10° F.) for the freezer compartment 18 and thirty degrees Fahrenheit (30° F.) for the fresh-food compartment 14, heat pump system 52 may theoretically be fifteen percent more efficient than known dual heat exchanger systems. It will be understood that only one of fresh-food compartment 14 and freezer compartment 18 may be actively cooled by heat pump system 52 at any particular time. The speed and/or the duty cycle of heat pump 100 can be programmatically matched to the required load of each compartment with minimal effect on efficiency. Alternatively, both fresh-food compartment 14 and freezer compartment 18 may be actively cooled by heat pump system 52 at any particular time.

FIG. 10 provides a schematic view of certain components of heat pump 100 according to another exemplary embodiment of the present subject matter. Heat pump 100 includes similar component and operates in a similar manner to that descried above. However, first stage 130 has a first section 192 and a second section 194. First and second sections 192, 194 of first stage 130 are spaced or separate, e.g., along the longitudinal direction O. In particular, first section 192 may be positioned at first end portion 144 of regenerator housing 140, and second section 194 may be positioned at second end portion 146 of regenerator housing 140. First cold side connection 150 may be positioned between first and second sections 192, 194. It will be understood that first stage 130 may be continuous between first and second sections 192, 194 or first and second sections 192, 194 may be separated by a gap, e.g., at first cold side connection 150.

First and second sections 192, 194 are differently sized and/or formed. For example, first and second sections 192, 194 may have different cross-sectional areas, e.g., in parallel planes that are perpendicular to the longitudinal direction O. In particular, first section 192 may have a larger cross-sectional area than second section 194, e.g., along the longitudinal direction O. As another example, first and second sections 192, 194 may have different lengths, e.g., along the longitudinal direction O. In particular, first section 192 may be longer than second section 194, e.g., along the longitudinal direction O. Thus, first section 192 may be larger than second section 194, e.g., such that a temperature differential of working fluid flowing through first section 192 is greater than through second section 194. In particular, the size of first section 192 (e.g., cross-sectional area, length, etc.) may be matched to a flow of working fluid through first section 192. Second section 194 may also be sized to match a flow of working fluid through second section 194. First and second sections 192, 194 may be common caloric materials or may be different caloric materials, e.g., such that a temperature gradient of working fluid is different within first and second sections 192, 194.

As may be seen in FIG. 10, regenerator housing 140 may have a joint 196 between first and second sections 192, 194. Joint 196 is tapered. In particular, joint 196 may taper or converge from first section 192 to first cold side connection 150, and joint 196 may also taper or converge from second section 194 to first cold side connection 150. Such tapering encourages mixing of returning working fluid at first cold side connection 150 and reduces dead volume within regenerator housing 140.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A refrigerator appliance, comprising: a cabinet defining a fresh food chamber and a freezer chamber; a fresh food cold side heat exchanger positioned within the cabinet at the fresh food chamber, the fresh food chamber chillable with air from the fresh food cold side heat exchanger; a freezer cold side heat exchanger positioned within the cabinet at the freezer chamber, the freezer chamber chillable with air from the freezer cold side heat exchanger; a regenerator housing having a first cold side connection and a second cold side connection, the first cold side connection separate from the second cold side connection on the regenerator housing; and a caloric material disposed within the regenerator housing, working fluid flowable through the caloric material within the regenerator housing; wherein the working fluid is flowable from the regenerator housing to the fresh food cold side heat exchanger via the first cold side connection and to the freezer cold side heat exchanger via the second cold side connection.
 2. The refrigerator appliance of claim 1, wherein the regenerator housing extends between a first end portion and a second end portion along a longitudinal direction, the first cold side connection spaced from the second cold side connection along the longitudinal direction on the regenerator housing.
 3. The refrigerator appliance of claim 2, further comprising a hot side heat exchanger, the regenerator housing having a hot side connection, the working fluid flowable from the regenerator housing to the hot side heat exchanger through the hot side connection.
 4. The refrigerator appliance of claim 3, wherein the hot side connection is positioned at the first end portion of the regenerator housing, the second cold side connection positioned at the second end portion of the regenerator housing, the first cold side connection positioned between the hot side connection and the second cold side connection along the longitudinal direction.
 5. The refrigerator appliance of claim 4, further comprising: a first cold side working fluid supply conduit extending between the first cold side connection and an inlet of the fresh food cold side heat exchanger; a first cold side working fluid return conduit extending between the first cold side connection and an outlet of the fresh food cold side heat exchanger; a second cold side working fluid supply conduit extending between the second cold side connection and an inlet of the freezer cold side heat exchanger; a second cold side working fluid return conduit extending between the second cold side connection and an outlet of the freezer cold side heat exchanger; a hot side working fluid supply conduit extending between the hot side connection and an inlet of the hot side heat exchanger; and a hot side working fluid return conduit extending between the hot side connection and an outlet of the hot side heat exchanger.
 6. The refrigerator appliance of claim 1, further comprising: a first cold side working fluid supply conduit extending between the first cold side connection and an inlet of the fresh food cold side heat exchanger; a first cold side working fluid return conduit extending between the first cold side connection and an outlet of the fresh food cold side heat exchanger; a second cold side working fluid supply conduit extending between the second cold side connection and an inlet of the freezer cold side heat exchanger; and a second cold side working fluid return conduit extending between the second cold side connection and an outlet of the freezer cold side heat exchanger.
 7. The refrigerator appliance of claim 6, further comprising a first pump and a second pump, the first pump coupled to the first cold side working fluid supply conduit or the first cold side working fluid return conduit, the first pump operable to flow the working fluid from the regenerator housing to the fresh food cold side heat exchanger via the first cold side connection, the second pump operable to flow the working fluid from the regenerator housing to the freezer cold side heat exchanger via the second cold side connection.
 8. The refrigerator appliance of claim 1, wherein the fresh food cold side heat exchanger is positioned within the cabinet at the fresh food chamber, the freezer cold side heat exchanger positioned within the cabinet at the freezer chamber.
 9. The refrigerator appliance of claim 8, further comprising a fresh food fan and a freezer fan, the fresh food fan operable to flow air across the fresh food cold side heat exchanger to the fresh food chamber, the freezer fan operable to flow air across the freezer cold side heat exchanger to the freezer chamber.
 10. The refrigerator appliance of claim 1, wherein the first cold side connection is positioned on the regenerator housing such that air at the fresh food cold side heat exchanger is about negative ten degrees Fahrenheit when the working fluid flows from the regenerator housing to the fresh food cold side heat exchanger through the first cold side connection, the second cold side connection positioned on the regenerator housing such that air at the freezer cold side heat exchanger is about thirty degrees Fahrenheit when the working fluid flows from the regenerator housing to the freezer cold side heat exchanger through the second cold side connection.
 11. The refrigerator appliance of claim 1, wherein the regenerator housing extends between a first end portion and a second end portion along a longitudinal direction, the caloric material having a first section at the first end portion of the regenerator housing and a second section at the second end portion of the regenerator housing, the first and second sections of the caloric material having different cross-sectional areas along the longitudinal direction, the first cold side connection positioned between the first and second sections of the caloric material.
 12. The refrigerator appliance of claim 11, wherein the regenerator housing has a joint between the first and second sections of the caloric material, the joint tapering from the first section of the caloric material to the first cold side connection, the joint also tapering from the second section of the caloric material to the first cold side connection.
 13. The refrigerator appliance of claim 1, wherein the regenerator housing extends between a first end portion and a second end portion along a longitudinal direction, the caloric material having a first section at the first end portion of the regenerator housing and a second section at the second end portion of the regenerator housing, the first and second sections of the caloric material having different lengths along the longitudinal direction, the first cold side connection positioned between the first and second sections of the caloric material.
 14. The refrigerator appliance of claim 13, wherein the regenerator housing has a joint between the first and second sections of the caloric material, the joint tapering from the first section of the caloric material to the first cold side connection, the joint also tapering from the second section of the caloric material to the first cold side connection.
 15. A refrigerator appliance, comprising: a cabinet defining a fresh food chamber and a freezer chamber; a fresh food cold side heat exchanger positioned within the cabinet at the fresh food chamber, the fresh food chamber chillable with air from the fresh food cold side heat exchanger; a freezer cold side heat exchanger positioned within the cabinet at the freezer chamber, the freezer chamber chillable with air from the freezer cold side heat exchanger; a regenerator housing; a caloric material disposed within the regenerator housing, working fluid flowable through the caloric material within the regenerator housing; and means for flowing the working fluid from the regenerator housing to the fresh food cold side heat exchanger and for separately flowing the working fluid from the regenerator housing to the freezer cold side heat exchanger.
 16. The refrigerator appliance of claim 15, wherein the means for flowing the working fluid comprises a first cold side connection and a second cold side connection on the regenerator housing, the working fluid flowable from the regenerator housing to the fresh food cold side heat exchanger via the first cold side connection and to the freezer cold side heat exchanger via the second cold side connection, the first cold side connection longitudinally spaced from the second cold side connection on the regenerator housing.
 17. The refrigerator appliance of claim 16, further comprising a hot side heat exchanger, the regenerator housing having a hot side connection, the working fluid flowable from the regenerator housing to the hot side heat exchanger through the hot side connection, the first cold side connection positioned between the hot side connection and the second cold side connection on the regenerator housing.
 18. The refrigerator appliance of claim 17 further comprising: a first cold side working fluid supply conduit extending between the first cold side connection and an inlet of the fresh food cold side heat exchanger; a first cold side working fluid return conduit extending between the first cold side connection and an outlet of the fresh food cold side heat exchanger; a second cold side working fluid supply conduit extending between the second cold side connection and an inlet of the freezer cold side heat exchanger; a second cold side working fluid return conduit extending between the second cold side connection and an outlet of the freezer cold side heat exchanger; a hot side working fluid supply conduit extending between the hot side connection and an inlet of the hot side heat exchanger; and a hot side working fluid return conduit extending between the hot side connection and an outlet of the hot side heat exchanger.
 19. The refrigerator appliance of claim 18, further comprising a first pump and a second pump, the first pump operable to flow the working fluid from the regenerator housing to the fresh food cold side heat exchanger via the first cold side connection, the second pump operable to flow the working fluid from the regenerator housing to the freezer cold side heat exchanger via the second cold side connection.
 20. The refrigerator appliance of claim 15, wherein the regenerator housing extends between a first end portion and a second end portion along a longitudinal direction, the caloric material having a first section at the first end portion of the regenerator housing and a second section at the second end portion of the regenerator housing, the first cold side connection positioned between the first and second sections of the caloric material, the regenerator housing having a joint between the first and second sections of the caloric material, the joint tapering from the first section of the caloric material to the first cold side connection, the joint also tapering from the second section of the caloric material to the first cold side connection. 